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A cord is used to lower vertically a block of mass M a distance d at a constant downward acceleration of g/4. (a) Find the work done by the cord on the block. (b) Find the work done by the force of gravity.

Amit Saxena

11 Years agoGrade upto college level

3 Answers

Navjyot Kalra

11 Years ago

Amiyanshu

8 Years ago

Check the net force on the object and then write the equation of motion.Tension and gravity are working on the object and motion is in direction of gravity. Hence the equation of motion is,Mg-T= ma. -(1)As the acceleration of the object is given as he as the acceleration of the object is given as G divided g divided by 4.T=3mg/4(A) work done =force×displacementAs we know that displacement is in opposite direction of force.Hence workdone is (-ve).W=-f.dW=-(3/4)×Mg×d(B) now work done by gravity is in direction of displacement hence it is positive.W=force(of gravity)×displacement W=Mgd

Kushagra Madhukar

5 Years ago

Dear student,

Please find the solution to your problem.

We have,

T – Mg = Ma

T = Mg + M( – g/4)

= ¾ Mg

Hence, work done by tension, W_T = T.(–d) = – Td

= – ¾ Mgd

The work done by Gravity, W_g = F_g.(d)

= Mgd

Thanks and regards,

Kushagra

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